Additional methods

This article describes the additional methods in the Datafeed API. With methods, you can enable additional features such as marks and a countdown to the bar close.

getMarks

The library calls getMarks to request marks for the visible bar range. The library assumes that you call GetMarksCallback once per getMarks call. Pass an array of Mark objects as a callback parameter.

Only ten marks can be attached to a bar. The time of each mark must match the time of a bar. For example, if the bar times are 2023-01-01, 2023-01-08, and 2023-01-15, then a mark cannot have the time 2023-01-05.

caution

This method is called only if your datafeed supports marks.

The code sample below demonstrates the example of getMarks implementation:

getMarks = (symbolInfo, startDate, endDate, onDataCallback, resolution) => {
    console.log('getMarks');

    onDataCallback(
        [
            {
                id: 1,
                time: endDate,
                color: 'red',
                text: ['This is the mark pop-up text.'],
                label: 'M',
                labelFontColor: 'blue',
                minSize: 25
            },
            {
                id: 2,
                time: endDate + 5260000, // 2 months
                color: 'red',
                text: ['Second marker'],
                label: 'S',
                labelFontColor: 'green',
                minSize: 25
            }
        ]);
};

getTimescaleMarks

The library calls getTimescaleMarks to request timescale marks for the visible bar range. The library assumes that you call GetMarksCallback once per getTimescaleMarks call. Pass an array of TimescaleMark objects as a callback parameter.

caution

These method is called only if your datafeed supports marks.

The code sample below demonstrates the example of getTimescaleMarks implementation:

getTimescaleMarks = (
    symbolInfo,
    startDate,
    endDate,
    onDataCallback,
    resolution
) => {
    // optional
    console.log('getTimescaleMarks');

    let marks = [];

    if (symbolInfo.name === 'AAPL') {
        marks = [
            {
                id: 1,
                time: startDate,
                color: 'red',
                label: 'Aa',
                minSize: 30,
                tooltip: [
                    'Lorem',
                    'Ipsum',
                    'Dolor',
                    'Sit',
                ]
            },
            {
                id: 2,
                time: startDate + 5260000, // 2 months
                color: 'blue',
                label: 'B',
                minSize: 30,
                tooltip: [
                    'Amet',
                    'Consectetur',
                    'Adipiscing',
                    'Elit',
                ]
            }
        ];
    } else {
        marks = [
            {
                id: 'String id',
                time: endDate,
                color: 'red',
                label: 'T',
                tooltip: ['Nulla']
            }
        ];
    }

    onDataCallback(marks);
};

getServerTime

By default, the library gets the time from the user's machine. If the machine time is incorrect, the time used in the library is also incorrect. To synchronize the library time with a server's time, enable the supports_time property and implement the getServerTime method. In the implementation, send a request to a time server and return the accurate value to the library using the ServerTimeCallback. The time value should be a Unix timestamp, for example, 1445324591. Note that the callback should be called only once.

The library allows you to display the countdown to the bar closing on the price scale. If you use this feature, consider implementing getServerTime to make sure that the countdown is correct.

info

To display a countdown, set the mainSeriesProperties.showCountdown property to true. Note that the countdown can be displayed only for intraday resolutions.

getVolumeProfileResolutionForPeriod

The library calls getVolumeProfileResolutionForPeriod to request the resolution that is used to calculate the Volume Profile Visible Range indicator. Implement this method if you want to calculate the indicator more accurately. The implementation depends on how much data you can transfer to the library and the depth of data in your datafeed.

If this method is not specified, the library uses currentResolution.